1. Field of the Invention
The present invention relates to a multicore optical fiber in which a plurality of core regions are arranged on the same cross section as a transmission medium for optical communications.
2. Related Background Art
As optical fiber networks have recently been increasing their traffic volume, attention has been focused on the use of multicore optical fibers (MCF) containing a number of cores within a cladding region. As an example of the multicore optical fibers, FIG. 7 of Y. KOKUBU and M. KOSHIBA, “Heterogeneous uncoupled and homogeneous coupled multicore fibers”, BS-7-7, IEICE2009, Sep. 15-Sep. 18, 2009) (Document 1) illustrates a multicore optical fiber in which a coupled core group constituted by densely arranging a plurality of cores having the same refractive index and the same core diameter is separated from its adjacent coupled core group by an uncoupled distance which can prevent crosstalk from occurring therebetween.